Telefunken RE 78 (RTV)
DC Amplifier Triode
1920

This RE 78 has an RTV label (Reichstelegraphen verwaltung). The RTV was a German goverment agency that controlled and licensed all electronic communications equipment at that time. The RTV label indicated that this tube was sold as a replacement item and that the tax had been paid. OEM tubes were covered under the end equipment license.